**Keywords:** water jet vacuum pump, new high-efficiency steam jet vacuum pump, steam jet series vacuum pump, jet water jet pump, chemical technology, application
**Abstract:**
Vacuum technology is widely applied in industries such as petroleum, chemical, and pharmaceutical through processes like evaporation, crystallization, distillation, sublimation, drying, concentration, dehydration, and material conveying. The use of vacuum technology in these processes helps save energy, speed up reactions, improve product quality, and increase economic benefits. As a result, vacuum technology has become an essential part of modern industrial practices. In China, the vacuum industry has absorbed technologies from the former Soviet Union, the United States, Japan, and Germany, developing products based on these foundations. However, despite the increasing number of vacuum equipment manufacturers in China, many lack clarity in selecting the appropriate vacuum pumps for different applications. This often leads to difficulties for users in choosing the right equipment. Based on over 30 years of experience in production, development, and support, this article discusses how to select jet vacuum pumps in several typical chemical processes.
**First, Key Concepts of Vacuum Pumps**
To effectively apply a vacuum pump in chemical production, it's important to understand the following concepts:
1. **Vacuum**: Refers to a state where gas pressure is below atmospheric pressure in a given space. It means the density of gas molecules is lower than that of the surrounding atmosphere. An absolute vacuum is a space with no gas at all.
2. **Vacuum Pump**: A device used to generate, improve, or maintain a vacuum.
3. **Pumping Capacity**: The amount of gas pumped per unit time by the vacuum pump, measured in kg/h or m³/h.
4. **Ultimate Pressure (Vacuum)**: The lowest pressure a vacuum pump can achieve when no gas is being extracted. Measured in Pa, kPa, MPa, or mmHg.
5. **Working Pressure (Vacuum)**: The absolute pressure at which the jet pump operates. Measured in Pa, kPa, MPa, or mmHg.
6. **Steam Working Pressure**: The pressure of the steam used in a steam jet vacuum pump. Measured in MPa or kgf/cm².
7. **Steam Consumption**: The amount of steam consumed per unit time by the steam jet vacuum pump. Measured in kg/h.
8. **Cooling Water Temperature**: The temperature of circulating water in a water jet pump or condenser in a steam jet vacuum pump. Measured in °C.
9. **Cooling Water Flow Rate**: The volume of water flowing through the pump per unit time. Measured in kg/h.
**Second, Common Vacuum Pumps in the Chemical Industry and Their Advantages and Disadvantages**
1. **Common Types of Vacuum Pumps**
In the chemical industry, vacuum pumps are generally divided into two categories: variable volume pumps and jet pumps. Variable volume pumps operate by changing the volume of the pump chamber to draw in and expel gas. Examples include reciprocating, rotary vane, slide valve, water ring, and Roots pumps. Jet pumps, on the other hand, use the Venturi effect to create a vacuum by accelerating a high-speed jet of fluid. Examples include water jet, steam jet, and combined jet pumps.
2. **Advantages and Disadvantages of Variable Volume Pumps**
- **Reciprocating, Rotary Vane, Slide Valve, and Roots Pumps**: These pumps work by moving parts to compress and expel gas. They offer high vacuum levels but suffer from wear and tear, leading to reduced performance over time. They also have high maintenance costs, noise, and fuel consumption.
- **Water Ring Pump**: Uses a rotating impeller and water to create a vacuum. It can handle condensable gases and is relatively simple in design. However, it cannot achieve high vacuum levels and is not suitable for corrosive or abrasive media.
3. **Advantages and Disadvantages of Jet Vacuum Pumps**
Jet pumps are increasingly used due to their wide vacuum range, ability to handle condensable gases and particulates, and low maintenance requirements. They include water jet, steam jet, and combined jet systems. Each type has its own working principle and application scope.
**Third, How to Choose a Suitable Vacuum Pump**
In chemical processes, the selection of a vacuum pump should be based on the required pressure level and the nature of the gas being pumped. For example, high vacuum is needed for distillation and sublimation, while lower vacuum levels are sufficient for evaporation, drying, and dehydration. The size of the gas flow and the presence of condensable or non-condensable gases also influence the choice.
**Fourth, Application Examples**
Several companies have successfully implemented jet vacuum pumps in their processes. For instance, Rugao Double Horse Chemical Co., Ltd. replaced three-stage steam jet pumps with water jet pumps for evaporation. Another company, Jiangsu Dingding Chemical Co., Ltd., used an intercooled soda combination jet pump to replace four steam jet pumps in fatty acid distillation. These examples demonstrate the versatility and efficiency of jet vacuum pumps in various chemical applications.
**Fifth, Conclusion**
As energy issues become more prominent, enterprises are focusing on energy efficiency and cost reduction. Choosing the right jet vacuum pump can significantly reduce operating costs and enhance competitiveness. This paper aims to provide practical guidance for the rational use of vacuum pumps in chemical processes.
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